We wish to investigate a set of conjectures on the structure of DNA in the compact state found in chromosomes, cell nuclei and globular viruses by means of an in vitro system simulating some aspects of the in vivo conditions. We hope to determine the extent of correspondence of the compact state with the usual mode of crystallization of simple linear polymers, and the particular roles of the DNA-binding proteins in promoting or stabilizing that state. A preliminary study of the binding equilibria of these proteins to DNA will be required to determine the simple binding parameters and also evidence for cooperativity, interactions between proteins, multiple connections to DNA, and the dependence on simple ions. The rate and extent of DNA folding will be studied following the procedures of our recent work on the folding of pure DNA in concentrated solutions of simple polymers. Unimolecular conformation changes are indicated by sedimentation rate measurements at very low DNA concentration, and the bulk folded state is observed by its anomalous circular dichroism. Molecular electron microscopy will be applied to some simple DNA-protein complexes.